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Finding the Fourth Proportional to 1,390.71, 2,086.08 and 659.89

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Solution

The fourth proportional to 1,390.71, 2,086.08 and 659.89 is: 989.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.71 : 2,086.08 = 659.89 : x
  2. Step 2: Convert to fraction form
    1,390.71/2,086.08 = 659.89/x
  3. Step 3: Cross multiply
    1,390.71x = 2,086.08 × 659.89
  4. Step 4: Simplify right side
    1,390.71x = 1,376,583.46
  5. Step 5: Solve for x
    x = 1,376,583.46/1,390.71
  6. Step 6: Final answer
    x = 989.84

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.